The present invention relates to the field computer-aided design (CAD), computer aided manufacturing (CAM), and computer aided engineering (CAE), and more particularly to systems and methods for performing freeform modeling operations in this field.
In the field of design, freeform modeling is employed to model solids or surfaces with respect to given aesthetic, functional, engineering or manufacturing constraints. Surface modeling is a significant part of the design of products in the automotive, aerospace and consumer goods industries, among others. In the automotive industry, it plays a major role in what is known as Class A parts, that is, those surfaces that are visible to the consumer. The automotive industry employs highly skilled stylists to design such surfaces. The major part of the work performed by such personnel is usually directed towards modifications of a previously designed surface or connected set of surface entities (called patches) rather than towards re-creating new designs from scratch. The stylists interactively work on the patches through a set of commands, such as the Control Point Modification command, the Matching command, the Extrapolation command and the Offset command, until the resulting overall shape of the surface is found satisfactory from an aesthetic viewpoint, according to engineering constraints such as accuracy and technical feasibility. A modification to the geometry of one patch usually impacts other parts of the geometry. However, the user does not know in advance the overall or global effect of a local modification to a patch. Therefore, to arrive at a final design that satisfies not only the design requirements for each patch, but also satisfies the design requirements for the overall surface, the user must engage in an iterative optimization sequence by manually alternating between individual commands. This work requires hundreds, if not thousands, of commands and iterations per workday.
In known freeform modeling applications, moving from one command to the next requires most often quitting the current command, selecting a new object and launching the new command, which will be applied to the new object. Although each of these actions may appear to take little time in itself, it means a considerable burden on productivity when they have to be repeated a thousand times a day. The amount of time spent by designers just on this command switching activity may represent up to 80 percent of the designing time. There is therefore a strong demand from users for improved tools to increase the productivity in the interactive modifications of geometry in freeform modeling operations.